New York Agricultural Experiment Station. 351 



quite clear. A striking change in color such as phytic acid suffers 

 in drying or on mere keeping either in the desiccator or under 

 ordinary conditions would very likely indicate a more or less serious 

 decomposition. 



In order to determine to what extent decomposition occurs it 

 was decided to make a series of inorganic phosphoric acid determina- 

 tions by the usual molybdate method on phytic acid preparations 

 before and after drying. While absolute accuracy could hardly 

 be expected or claimed for this method, at least comparable results 

 would be obtained when the precipitations were done under similar 

 conditions. 



One portion of the acid was dried at 105° in vacuum over phos- 

 phorus pentoxide to constant weight. It was then dissolved in 

 water, neutralized with ammonia, acidified with nitric acid, ammonium 

 nitrate added and heated to 65°. Ammonium molybdate was then 

 added and kept at above temperature for 1 hour. The precipitate 

 was then determined as magnesium pyrophosphate in the usual way. 



Another portion was treated in the same manner without drying, 

 the amount of moisture found on drying as above being deducted 

 from the weight taken. 



The acid analyzed on page 32 was used for the first determinations. 

 The fresh preparation, dried in vacuum over sulphuric acid as 

 described, contained about 15 per ct. of water and it gave no reaction 

 with ammonium molybdate. It was allowed to stand in the labora- 

 tory at summer temperature (about 80° or 90° Fahr.) in a loosely 

 covered dish for three or four weeks. The color had then changed 

 to light brown. On drying at 105° in vacuum over phosphorus 

 pentoxide for about 24 hours to constant weight it lost about 22 

 per ct. of its weight, showing that it had absorbed about 7 per ct. 

 of water during this time. The acid, page 32, contained 27.31 per ct. 

 of phosphorus. The dried preparation gave the following as inor- 

 ganic phosphate: 



0.2508 gram dry subst. gave 0.0696 gram Mg 2 P 2 7 , equivalent 

 to 7.73 per ct. phosphorus or 28.30 per ct. of the total phosphorus 

 was precipitated as inorganic phosphoric acid. 



Before drying: 



0.1889 gram (dry subst. calculated) gave 0.0039 gram Mg 2 P 2 7 , 

 equivalent to 0.57 per ct. of phosphorus or 2.08 per ct. of total 

 phosphorus. 



As will be noticed from the above figures, 26.2 per ct. of the total 

 phosphorus had been hydrolyzed by drying at 105° for about 24 

 hours. 



An old sample of phytic acid which had been kept in the laboratory 

 for about 18 months was examined in the same manner. It was 

 practically black in color. It lost about 22 per ct. of its weight on 



